fend: add install check

This checks if the binary is working correctly.

pkgs/tools/misc/fend/default.nix

@@ -13,6 +13,12 @@ rustPlatform.buildRustPackage rec {
 
   cargoSha256 = "sha256-e95DRhD22zvizUJOM2It45Bx05iK3KtaMgFPkMbR7iI=";
 
+  doInstallCheck = true;
+
+  installCheckPhase = ''
+    [[ "$($out/bin/fend "1 km to m")" = "1000 m" ]]
+  '';
+
   meta = with lib; {
     description = "Arbitrary-precision unit-aware calculator";
     homepage = "https://github.com/printfn/fend";